Jarring tool



' April 6, 1943.

G. N. STAFFORD I 2,315,905l

JARRING TOOL Filed March 1, 1940 29 if@ t 15h31? 25;;32 Z9 fog w z5 Z9 Z2 a w/ /Y 57,4 Froe; I N VEN TOR.

Patented Apr. 6, 1943 UNITED STATES PATENT OFFICEl JABRJNG TOOL Guy N. Stafford, Gardena, Calif., assigner to J. McCullough, Los Angeles, Calif.

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Application March 1, 1940, serial No. 321,737 4 Claims. (Cl. Z55-27) My invention relates to jars of the type employed in wells to move objects which are stuck in such wells, and relates in particular to a. simple Jar especially adapted for use in the cable system of well drilling.

It is an object of the invention to provide a jar which may be employed in a tool line which is suspended or lowered into the well. By tool line I means a tool and the suspension means whereby the tool is lowered into the Well so that it may be operated. In the practice of the invention the tool may be a drill bit, bailer or swab, or other device which is lowered into a well and which during its operation might become stuck therein. The jar is of such character that it may be a constant part of the tool line so that if at any time the tool of the tool line becomes stuck, the jar may be employed to move the same from the position in which it is lodged.

It is an object of the invention to provide a jar of the character described in the preceding paragraph having cooperating parts preferably in telescopic relation and connected for limited axial movement and having cooperating shoulders which are brought into engagement by relative axial movement of the members so as to impart jarring blows. A special feature of the invention is the provision of a simple movement restraining or retarding means having no cams or shoulders but merely a simple arrangement of parts which retard the movement of the jar member while tension is being applied to the tool line.

An object of the invention is to provide a jar of the above character having movement restraining or retarding means which for its effect depends upon the hydrostatic pressure of iiuid or liquid in the well to exert a force tending to hold cooperating parts against movement during the time a strain is being applied, so that when the cooperating parts are released for jarring movement a relatively sharp and heavy blow will be struck and a correspondingly effective force will be applied to move the object with which the jar is connected. For example, the object to be jarred may be the drill `bit. When the bit becomes stuck, the jar, which `is mounted adjacent the upper end of the bit, may be actuated by an up and down movement of the cable. In the operation of the jar, the cable is rst lowered so that the upper sliding member ofthe jar may move downward on the lower jar member to eiect engagement of the cooperating parts of the retarding or restraining means of the jar. An upward pull is then applied to the cable so as to build up a tension therein prior to the release of the restraining or retarding means. This tension in the cable causes an elongation thereof, and when the restraining or retardin'g means releases, the contraction of the suspension means, namely, the cable, produces a rapid and forcible upward movement of the upper jarring member so that a heavy jarring blow results from the shoulder of the upper jarring member striking the shoulder of the lower jarring member which is connected to the bit. As hereinbefore indicated the jar may be employed as a constant part of a tool line wherein the tool comprises a bailer which is lowered to the bottom of the well i'or the purpose of bailing from the bottom of the well materials which may be of such character that sticking of the bailer is a constant hazard. Having the jar at all times ready for immediate use is of material advantage -for the reason that the jarring operations may be started before any large degree ofsettling of solids around or above the tool has time tooccur.

It is an object of the invention to provide a restraining or retarding means for a Jar of the general character hereinabove described comprising a hollow bodyhaving an opening into which a plug may slide, thereby forming a. chamber in which a pressure reduction occurs when a force is applied tending to move the plug out of the opening, so that the hydrostatic pressure applied to the outer end of the plug will exert a force tending to hold the plug in the opening.

A further object of the invention isto provide a retarding or restraining means of the character set forth in the preceding paragraph having check valve means for permitting escape cf iiuid from the chamber as the plug is moved into the opening of the hollow body, and a further object is to provide a device of this character having the cooperating parts so arranged or having means for p'ermitting a limited :Elow of fluid into the chamber to effect a reduction in the differential of pressure between the exterior and the interior of the device whereby release oi the plug from the chambermay be eilectuated.

Further objects and advantages of the invention will be brought out in the following part of the specification.

Referring to the drawing which is for illustrative purposes only:

Fig. 1 is an assembly view of a simple form of my invention, partly sectioned, and with intermediate portions of the device cut out to reduce the overall length of the view.

A' As shown an upper part III, and a lower part II connected Fig. 2 is a cross-section taken` on the plane represented by the line 2-2 o! Fig. 1.

Fig. 3 is a cross-section on the plane indicated bythellnel-JofFlgJ.

in the drawing, the jar comprises for axial sliding movement. The upper part Il is provided with external means of joinder, shown as a threaded pin I2,v whereby it may be connected to a suspension member such as a cable extended down into the well from the hoisting means of the derrick. The lower part I I is shown with external means of joinder I3, whereby it may be connected to a downwardly extending part of the tool line. Such means of joinder I3 is shown as a head having internal threads Il whereby it may be secured to the upper end of a tool, such as a drill bit, a socket, or a bailer. The upper part is shown as extending down over and around the upper portion of the lower part, which, in the use oi! the jar, remains stationary or relatively so due to the tact that it is connected to the upper end of the part to which the jarring eiect is to be applied. When the upperl part III is lowered relative to the lower part II cooperating movement retarding or restraining means on the two parts comes into engagement so that the upper part will be restrained from upward movement, or in other words will be in set position. These cooperating parts, when they come into engagement, form a chamber in which a. reduced pressure, partial vacuum or full vacuum may be effectuated, so that the external hydrostatic pressure exerted by the column of liquid in the well will tend to hold these cooperating parts against separation. Separation of the parts when a pull is exerted tending to raise the upper jar part IIJ relative to the lower jar part Il may be accomplished either by exerting an upward pull greater than the force resulting from the external hydrostatic pressure tending to hold the cooperating parts of the restraining means together, or by increasing the pressure in the chamber by allowing an entry of uid thereinto.

In the form oi.' the invention shown, the cooperating parts of the restraining means are built into the jar structure and are shown as consisting oi a plug or piston I5 carried on or forming the upper end of the lower part II, and a hollow body forming a shell or cylinder I6 comprising a portion .of the upper jar part I0. In my present simple construction the cylinder I6 comprises the upper part of a steel tube I1 having at the lower end thereof an annular wall I8 providing a shoulder or anvil I9, vertical slots 20 being cut in the tube I6 from the annular wall I8 to the lower end of the cylinder I6 to provide bars 2I extending downward from the lower end of the cylinder IE to support the annular wall IB in spaced relation to the lower end of the cylinder, wherein the distance from the shoulder I9 to the lower end of the cylinder will be materially greater than the vertical dimension or length of the piston I5. A plug 22 is screwed into the upper end of the tube I1, this plug having the threaded pin I2 formed thereon and also having Ia threaded opening 23 to receive a sleeve 24, the upper end of which forms a valve seat 25 for a closure member which may be in the form of a ball 26, thereby forming a check valve. An axial chamber 21 extends upward from the threaded opening 23 and has therein a spring 28 which exerts downward pressure against the ball 26. Discharge openings for thecheck valve are formed by radial holes 29 which lead outward from the chamber 21.

The lower jar part II includes a rod 30 which extends downward from the piston I5 through the opening 3l provided by the annular wall Il and is connected to the head I3 by a threaded joint 32. The piston I5 may be a relatively close nt in the cylinder I8, or the external diameter of the piston I5 may be made smaller than the internal diameter of the cylinder I8 so as to provide space between the piston and the wall of the cylinder through which a limited flow of liquid may occur, depending upon conditions of use, as will be brought out in the following part of the speciiication.

' For purpose of explanation let it be assumed that the jar is being used in a deep hole wherein the head of liquid in the Well produces a high hydrostatic pressure near the bottom of the hole, or, in other words in the zone in which the jar would be operated. To set the jar preparatory to the strikingr of a jarring blow, the upper part III is lowered on the lower part II so as to cause the piston I5 to pass into the shell I5, displacing therefrom, through the check valve at the upper end, the fluid trapped in the chamber 40 formed by the cylinder I6, the plug 22, and the piston I5. Upon completion of the step consisting of lowering of the upper mem-ber III to its lowered position on the member II, it will be found that the pressure in the chamber 40 is substantially equal to the external hydrostatic pressure, but should an upward force now be applied to the upper part ID, tending to enlarge the chamber 40 by moving the upper wall of the chamber formed by the plug 22 away from the piston, there will be an immediate reduction in pressure in the chamber 40, and if the piston I5 is a tight fit and the chamber 40 entirely closed, this upward movement of the member III will produce a vacuum in the chamber 40, providing, of course, the upward force applied to the upper member Ill is suiilcient to overcome the hydrostatic pressure exerted downwardly on the plug 22 and upwardly against the lower end of the piston I5 tending to prevent axial expansion of the chamber 4l). Under certain conditions of operation the hydrostatic force eifective is so large that a pull too great for safe operation must be transmitted through the suspension means to pull the cylinder I6 out of engagement with the piston I5. Under such circumstances I provide means for relieving the reduced pressure in the chamber 40 by admitting a limited flow of fluid into this chamber. This may be accomplished by use of a ported plug 4I screwed into a threaded opening 42 near the upper end of the cylinder I6. In lfact, a number of plugs for the opening 42 may be provided, one having no opening therein and the others having openings of dierent sizes for different inflows of fluid under various conditions of operation. However, in the general practice of my invention I may avoid the use of the plug 4I entirely, and make the piston -I5 of such di.

I6 brings the upper` ends d of the slots 2B into coincidence with the upper ends of the piston i5, a free ow of fluid from the exterior into the chamber t is permitted and the hydrostatic pressure against the upper and lower ends of the piston and the upper and lower ends of the plug 22 are balanced so that contraction of the suspension member may rapidly move the upper jar member lil upward so as to bring the anvil i8 into forcible engagement with the shoulder 66 constituting the lower end of the piston l5.

When the device is used in a shallow well, no means for permitting an entry of fluid into the chamber d@ need be provided since an excessive force will not be required to move the piston and cylinder out of engagement against the hydrostatic pressure differential.

I claim as my invention:

1. In a jar of the character described, for use in a tool line which extends into a well, the combination of: a cylinder having a wall closing one end thereof, said wall comprising attachment means for connecting it to a part oi" said line; an annular wall providing an anvil; means connecting said annular wall to said cylinder in a position spaced from the open end thereof, said means comprising a cylindric wall having an opening to connect the open end of said cylinder with the exterior of the jar; a piston siidable from a position in said cylinder wherein it defines a chamber within said cylinder, to a position outside said cylinder and within said cylindric wall wherein it will strike said anvil; a rod extending from said piston through said annular wall; an attachment means at the outer end of said rod for connecting it to another part of said line; and means limiting the entry of uid into said chamber when said piston is in said cylinder. whereby the fluid pressure differential acting against the exposed ends of said piston and said wall of said cylinder will resist relative movement of said piston toward said anvil until said piston is moved out of said cylinder.

2. In a jar of the character described, for use in a tool line which extends into a well. the combination of: a cylinder having a wall closing one end thereof, said wall comprising attachment means for connecting it to a part of said line; an annular wall providing an anvil; means connecting said annular wall to said cylinder in a position spaced from the open end thereof, said means comprising a tubular wall having a lateral opening extending from said open end of said cylinder to said annular wall; a piston slidable from a position in said cylinder wherein it defines a chamber within said cylinder, to a position outside said cylinder and within said tubular wall wherein it will strike said anvil; a rod extending from said piston through said annular wall; an attachment means at the outer end of said rod for connecting it to another part of said line; means limiting the entry of fluid into said chamber when said piston is in said cylinder, whereby the fluid pressure differential applied to the outer ends of said piston and said wall which closes said end of said cylinder will resist relative movement of said piston toward said anvil until said piston is moved out of said'cylinder; and check valve means for permitting a iicw of fluid out of said chamber as said piston is moved into said cylinder.

3. In a jar of the character described, the combination of a tubular shell closed at one end thereof; attachment means at the closed end of said shell; an anvil; means for supporting said anvil in spaced relation to the open end of said shell, said means having a lateral openinglto connect the open end of said shell with the exterior of the jar; a piston .slidable from a position within said shell wherein it defines a chamber within said shell, to a position outside said shell and within said means wherein it strikes said anvil; and a rod extending from said piston to a point beyond said anvil, said rod having attachment means at the outer end thereof, the cuter end of said piston being exposed to pressure of iluid exterior of said shell when said piston is in said shell, and the inner end of said piston being exposed to .the pressure in -said chamber, whereby the pressure diierential applied to the outer ends of said piston and said shell will restrain relative movement of said piston toward said anvil.

4. In a jar of the character described for use in i a weil having liquids therein, the combination of a tubular wall elongated in the direction of its axis and being closed at one end, said wall being laterally ported near its'othcr end whereby the tubular wall will be divided into a ported section and a chambered section forming a chamber in open communication with said ported section and communicating with the exterior of the jai' through said ported section; and an annular wall forming a shoulder at said other end of said tubular wall; a plunger member extending into said tubular wall through said other end thereof said plunger member having a piston on its inner end to move from a position in said chamber to a position in said ported section wherein it will strike said shoulder, there being means to permit an out-flow of liquid from said chamber when said piston is moved thereinto and means enabling a limited ow of liquid intov said chamber when a force is applied tending to move said piston out of said chamber against the hydrostatic pressure of liquid in the well against the outer end of said piston and the closed end of said tubular wall, and which resists movement of said piston out of said chamber.

GUY N. STAFFORD. 

